The Four Tubes

[aquaMat]

Hi Jackie,

thanks for playing The Four Tubes.

I have the strange feeling you didn't explore the area near the grey door in room 13504 properly. (That was a hint, BTW).

The upper level you mention, though important on its own, has no direct relevance to the door in question. (BTW, the

red lever

and

column

you mention are not even in the same room as the grey door.)
However, once you are up there you are on your way to the portion of room 13504 that leads to that grey door.

Please keep on trying......  and maybe don't try too much to avoid certain things that are meant to happen.  (Another cryptic advice.....  !!)